IHL’s Era of Application?

Today marks the 150th Anniversary of the signing of the first Geneva Convention — the Convention for the Amelioration of the Condition of the Wounded in Armies in the Field.  12 States signed it on August 22, 1864, and the treaty went on to have 57 parties before being replaced by later Geneva Conventions in 1906, 1929 and 1949.  The ICRC is using the occasion to make a call for more action on international humanitarian law and to spread knowledge about that law more generally (including a 4 minute video on the Rules of War in a Nutshell).  

It’s interesting to think about the full arc of IHL that this anniversary represents. It seems we’ve gone from decades of iteration — where States and others worked to hammer out what rules actually exist — to what is now much more an era of application.  Today’s IHL debates (many of which we’ve hosted here in recent weeks) regularly revolve around where, when and how specific rules apply to particular cases.  Or, they debate which rules exist only in treaty form versus those that have the status of customary international law.  Even in areas of new technology, the prevailing effort is to explain how existing rules govern by analogy (see, e.g., the Tallinn Manual).  These are all important and even laudatory causes.  But it does leave me with a question:  Is the corpus of IHL now largely complete, or should we expect another round of law generation akin to the Geneva Convention projects of 150 and 75 years ago?  Simply put, is there any new IHL to be made, and, if so, what should it be?